Re: [patch] mm: shmem: use new radix tree iterator

[Ric Mason]

Hi Hugh,
On 02/04/2013 10:01 AM, Hugh Dickins wrote:
> On Fri, 1 Feb 2013, Johannes Weiner wrote:
>
> > In shmem_find_get_pages_and_swap, use the faster radix tree iterator
> > construct from 78c1d78 "radix-tree: introduce bit-optimized iterator".
> >
> > Signed-off-by: Johannes Weiner <hannes@xxxxxxxxxxx>
> Yes, that looks fine, and is testing out fine, thanks.
> Acked-by: Hugh Dickins <hughd@xxxxxxxxxx>

Could you share your testcase with me? It seems that you always can test 
shmem patches.

> > ---
> >   mm/shmem.c | 25 ++++++++++++-------------
> >   1 file changed, 12 insertions(+), 13 deletions(-)
> >
> > diff --git a/mm/shmem.c b/mm/shmem.c
> > index a368a1c..c5dc8ae 100644
> > --- a/mm/shmem.c
> > +++ b/mm/shmem.c
> > @@ -336,19 +336,19 @@ static unsigned shmem_find_get_pages_and_swap(struct address_space *mapping,
> >   					pgoff_t start, unsigned int nr_pages,
> >   					struct page **pages, pgoff_t *indices)
> >   {
> > -	unsigned int i;
> > -	unsigned int ret;
> > -	unsigned int nr_found;
> > +	void **slot;
> > +	unsigned int ret = 0;
> > +	struct radix_tree_iter iter;
> > +
> > +	if (!nr_pages)
> > +		return 0;
> >   
> >   	rcu_read_lock();
> >   restart:
> > -	nr_found = radix_tree_gang_lookup_slot(&mapping->page_tree,
> > -				(void ***)pages, indices, start, nr_pages);
> > -	ret = 0;
> > -	for (i = 0; i < nr_found; i++) {
> > +	radix_tree_for_each_slot(slot, &mapping->page_tree, &iter, start) {
> >   		struct page *page;
> >   repeat:
> > -		page = radix_tree_deref_slot((void **)pages[i]);
> > +		page = radix_tree_deref_slot(slot);
> >   		if (unlikely(!page))
> >   			continue;
> >   		if (radix_tree_exception(page)) {
> > @@ -365,17 +365,16 @@ static unsigned shmem_find_get_pages_and_swap(struct address_space *mapping,
> >   			goto repeat;
> >   
> >   		/* Has the page moved? */
> > -		if (unlikely(page != *((void **)pages[i]))) {
> > +		if (unlikely(page != *slot)) {
> >   			page_cache_release(page);
> >   			goto repeat;
> >   		}
> >   export:
> > -		indices[ret] = indices[i];
> > +		indices[ret] = iter.index;
> >   		pages[ret] = page;
> > -		ret++;
> > +		if (++ret == nr_pages)
> > +			break;
> >   	}
> > -	if (unlikely(!ret && nr_found))
> > -		goto restart;
> >   	rcu_read_unlock();
> >   	return ret;
> >   }
> > --
> > 1.7.11.7
> --
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